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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package javax.management.openmbean;

// java import
//

import java.util.Arrays;

import javax.management.Descriptor;
import javax.management.MBeanConstructorInfo;
import javax.management.MBeanParameterInfo;


/**
 * Describes a constructor of an Open MBean.
 *
 * @since 1.5
 */
public class OpenMBeanConstructorInfoSupport
    extends MBeanConstructorInfo
    implements OpenMBeanConstructorInfo {

  /* Serial version */
  static final long serialVersionUID = -4400441579007477003L;


  // As this instance is immutable,
  // these two values need only be calculated once.
  private transient Integer myHashCode = null;
  private transient String myToString = null;

  /**
   * <p>Constructs an {@code OpenMBeanConstructorInfoSupport}
   * instance, which describes the constructor of a class of open
   * MBeans with the specified {@code name}, {@code description} and
   * {@code signature}.</p>
   *
   * <p>The {@code signature} array parameter is internally copied,
   * so that subsequent changes to the array referenced by {@code
   * signature} have no effect on this instance.</p>
   *
   * @param name cannot be a null or empty string.
   * @param description cannot be a null or empty string.
   * @param signature can be null or empty if there are no parameters to describe.
   * @throws IllegalArgumentException if {@code name} or {@code description} are null or empty
   * string.
   * @throws ArrayStoreException If {@code signature} is not an array of instances of a subclass of
   * {@code MBeanParameterInfo}.
   */
  public OpenMBeanConstructorInfoSupport(String name,
      String description,
      OpenMBeanParameterInfo[] signature) {
    this(name, description, signature, (Descriptor) null);
  }

  /**
   * <p>Constructs an {@code OpenMBeanConstructorInfoSupport}
   * instance, which describes the constructor of a class of open
   * MBeans with the specified {@code name}, {@code description},
   * {@code signature}, and {@code descriptor}.</p>
   *
   * <p>The {@code signature} array parameter is internally copied,
   * so that subsequent changes to the array referenced by {@code
   * signature} have no effect on this instance.</p>
   *
   * @param name cannot be a null or empty string.
   * @param description cannot be a null or empty string.
   * @param signature can be null or empty if there are no parameters to describe.
   * @param descriptor The descriptor for the constructor.  This may be null which is equivalent to
   * an empty descriptor.
   * @throws IllegalArgumentException if {@code name} or {@code description} are null or empty
   * string.
   * @throws ArrayStoreException If {@code signature} is not an array of instances of a subclass of
   * {@code MBeanParameterInfo}.
   * @since 1.6
   */
  public OpenMBeanConstructorInfoSupport(String name,
      String description,
      OpenMBeanParameterInfo[] signature,
      Descriptor descriptor) {
    super(name,
        description,
        arrayCopyCast(signature), // may throw an ArrayStoreException
        descriptor);

    // check parameters that should not be null or empty
    // (unfortunately it is not done in superclass :-( ! )
    //
    if (name == null || name.trim().equals("")) {
      throw new IllegalArgumentException("Argument name cannot be " +
          "null or empty");
    }
    if (description == null || description.trim().equals("")) {
      throw new IllegalArgumentException("Argument description cannot " +
          "be null or empty");
    }

  }

  private static MBeanParameterInfo[]
  arrayCopyCast(OpenMBeanParameterInfo[] src) {
    if (src == null) {
      return null;
    }

    MBeanParameterInfo[] dst = new MBeanParameterInfo[src.length];
    System.arraycopy(src, 0, dst, 0, src.length);
    // may throw an ArrayStoreException
    return dst;
  }


    /* ***  Commodity methods from java.lang.Object  *** */


  /**
   * <p>Compares the specified {@code obj} parameter with this
   * {@code OpenMBeanConstructorInfoSupport} instance for
   * equality.</p>
   *
   * <p>Returns {@code true} if and only if all of the following
   * statements are true:
   *
   * <ul>
   * <li>{@code obj} is non null,</li>
   * <li>{@code obj} also implements the {@code
   * OpenMBeanConstructorInfo} interface,</li>
   * <li>their names are equal</li>
   * <li>their signatures are equal.</li>
   * </ul>
   *
   * This ensures that this {@code equals} method works properly for
   * {@code obj} parameters which are different implementations of
   * the {@code OpenMBeanConstructorInfo} interface.
   *
   * @param obj the object to be compared for equality with this {@code
   * OpenMBeanConstructorInfoSupport} instance;
   * @return {@code true} if the specified object is equal to this {@code
   * OpenMBeanConstructorInfoSupport} instance.
   */
  public boolean equals(Object obj) {

    // if obj is null, return false
    //
    if (obj == null) {
      return false;
    }

    // if obj is not a OpenMBeanConstructorInfo, return false
    //
    OpenMBeanConstructorInfo other;
    try {
      other = (OpenMBeanConstructorInfo) obj;
    } catch (ClassCastException e) {
      return false;
    }

    // Now, really test for equality between this
    // OpenMBeanConstructorInfo implementation and the other:
    //

    // their Name should be equal
    if (!this.getName().equals(other.getName())) {
      return false;
    }

    // their Signatures should be equal
    if (!Arrays.equals(this.getSignature(), other.getSignature())) {
      return false;
    }

    // All tests for equality were successfull
    //
    return true;
  }

  /**
   * <p>Returns the hash code value for this {@code
   * OpenMBeanConstructorInfoSupport} instance.</p>
   *
   * <p>The hash code of an {@code OpenMBeanConstructorInfoSupport}
   * instance is the sum of the hash codes of all elements of
   * information used in {@code equals} comparisons (ie: its name
   * and signature, where the signature hashCode is calculated by a
   * call to {@code
   * java.util.Arrays.asList(this.getSignature).hashCode()}).</p>
   *
   * <p>This ensures that {@code t1.equals(t2)} implies that {@code
   * t1.hashCode()==t2.hashCode()} for any two {@code
   * OpenMBeanConstructorInfoSupport} instances {@code t1} and
   * {@code t2}, as required by the general contract of the method
   * {@link Object#hashCode() Object.hashCode()}.</p>
   *
   * <p>However, note that another instance of a class implementing
   * the {@code OpenMBeanConstructorInfo} interface may be equal to
   * this {@code OpenMBeanConstructorInfoSupport} instance as
   * defined by {@link #equals(java.lang.Object)}, but may have a
   * different hash code if it is calculated differently.</p>
   *
   * <p>As {@code OpenMBeanConstructorInfoSupport} instances are
   * immutable, the hash code for this instance is calculated once,
   * on the first call to {@code hashCode}, and then the same value
   * is returned for subsequent calls.</p>
   *
   * @return the hash code value for this {@code OpenMBeanConstructorInfoSupport} instance
   */
  public int hashCode() {

    // Calculate the hash code value if it has not yet been done
    // (ie 1st call to hashCode())
    //
    if (myHashCode == null) {
      int value = 0;
      value += this.getName().hashCode();
      value += Arrays.asList(this.getSignature()).hashCode();
      myHashCode = Integer.valueOf(value);
    }

    // return always the same hash code for this instance (immutable)
    //
    return myHashCode.intValue();
  }

  /**
   * <p>Returns a string representation of this {@code
   * OpenMBeanConstructorInfoSupport} instance.</p>
   *
   * <p>The string representation consists of the name of this class
   * (ie {@code
   * javax.management.openmbean.OpenMBeanConstructorInfoSupport}),
   * the name and signature of the described constructor and the
   * string representation of its descriptor.</p>
   *
   * <p>As {@code OpenMBeanConstructorInfoSupport} instances are
   * immutable, the string representation for this instance is
   * calculated once, on the first call to {@code toString}, and
   * then the same value is returned for subsequent calls.</p>
   *
   * @return a string representation of this {@code OpenMBeanConstructorInfoSupport} instance
   */
  public String toString() {

    // Calculate the string value if it has not yet been done (ie
    // 1st call to toString())
    //
    if (myToString == null) {
      myToString = new StringBuilder()
          .append(this.getClass().getName())
          .append("(name=")
          .append(this.getName())
          .append(",signature=")
          .append(Arrays.asList(this.getSignature()).toString())
          .append(",descriptor=")
          .append(this.getDescriptor())
          .append(")")
          .toString();
    }

    // return always the same string representation for this
    // instance (immutable)
    //
    return myToString;
  }

}
